| 摘要 |
PURPOSE:To form a very strong multipolar magnetostatic field on the surface of a molding cavity by a method wherein permanent magnets magnetized in the circumferential direction of the molding cavity are provided on the circumference of the molding cavity and magnetically soft material yokes are adjacently provided in such a way that the N poles and S poles of the magnets appear alternately on the surface of the molding cavity. CONSTITUTION:Permanent magnets 44a, 44b,... magnetized in the circumferential direction of an annular molding space 10 are disposed on the circumference of the molding space in large numbers. Moreover, these permanent magnets 44 are disposed in such a way that the magnetic poles of the same polarity are adjoined in the mutually adjoining permanent magnets. Moreover, yoke materials 45a, 45b,... consisting of a magnetically soft material are arranged between the permanent magnets. Accordingly, if one of the permanent magnets 44 is taken up as an example, the line of magnetic flux flowed out of this N pole passes through another yoke material 41 via the molding space 10 from the yoke mateiral 45 and is flowed in the S pole. By such a way, the N poles and the S poles can be alternately formed on the surface of the molding space. |
